Liquid crystal display and method of driving the same

ABSTRACT

A liquid crystal display and a method of driving the same are disclosed. The liquid crystal display includes a timing controller, N source drive integrated circuits (ICs), where N is an integer equal to or greater than 2, N pairs of data bus lines, each of which connects the timing controller to each of the N source drive ICs in a point-to-point manner, a lock check line that connects a first source drive IC of the N source drive ICs to the timing controller and cascade-connects the N source drive ICs to one another, and a feedback lock check line connecting a last source drive IC of the N source drive ICs to the timing controller. A swing width of an output voltage of the timing controller increases in proportion to a distance between the timing controller and the N source drive ICs.

This application claims the benefit of Korea Patent Application No.10-2008-0132466 filed on Dec. 23, 2008, which is incorporated herein byreference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the inventions relate to a liquid crystal display and amethod of driving the same.

2. Discussion of the Related Art

Active matrix type liquid crystal displays display a moving pictureusing a thin film transistor (TFT) as a switching element. The activematrix type liquid crystal displays have been implemented in televisionsas well as display devices in portable devices, such as office equipmentand computers, because of the thin profile of an active matrix typeliquid crystal displays. Accordingly, cathode ray tubes (CRT) are beingrapidly replaced by the active matrix type liquid crystal displays.

A liquid crystal display includes a plurality of source drive integratedcircuits (ICs) supplying a data voltage to data lines of a liquidcrystal display panel, a plurality of gate drive ICs sequentiallysupplying a gate pulse (i.e., a scan pulse) to gate lines of the liquidcrystal display panel, and a timing controller controlling the sourcedrive ICs and the gate drive ICs. In the liquid crystal display, digitalvideo data is input to the timing controller through an interface.

The timing controller supplies the digital video data, a clock forsampling the digital video data, a control signal for controlling anoperation of the source drive ICs, and the like to the source drive ICsthrough an interface such as a mini low-voltage differential signaling(LVDS) interface. The source drive ICs deserializes the digital videodata serially input from the timing controller to output parallel dataand then converts the parallel data into an analog data voltage using agamma compensation voltage to supply the analog data voltage to the datalines.

The timing controller supplies necessary signals to the source drive ICsusing a multi-drop manner of commonly applying the clock and the digitalvideo data to the source drive ICs. Because the source drive ICs arecascade-connected to one another, the source drive ICs sequentiallysample the digital video data and then simultaneously output datavoltages corresponding to 1 line. In such a data transfer method, manylines such as R, G, and B data transfer lines, control lines forcontrolling outputs of the source drive ICs and an operation timing of apolarity change of the source drive ICs, and clock transfer lines arenecessary between the timing controller and the source drive ICs.Because the mini LVDS interface is a manner of transferring each of thedigital video data and the clock in the form of a pair of differentialsignals, which are out of phase with each other, at least 14 datatransfer lines between the timing controller and the source drive ICsare necessary to simultaneously transfer odd data and even data.Accordingly, because many data transfer lines have to be formed on aprinted circuit board (PCB) positioned between the timing controller andthe source drive ICs, it is difficult to reduce the number of datatransfer lines.

Further, in the liquid crystal display, a deviation in a delay amount ofsignals input to the source drive ICs and a deviation in a voltage dropamount of the signals may be caused depending on a distance between thetiming controller and the source drive ICs.

SUMMARY OF THE INVENTION

Embodiments of the inventions provide a liquid crystal display and amethod of driving the same capable of compensating for a deviation in adelay amount of signals input to source drive integrated circuits (ICs)and a deviation in a voltage drop amount of the signals.

In one aspect, there is a liquid crystal display comprising a timingcontroller, N source drive integrated circuits (ICs), where N is aninteger equal to or greater than 2, N pairs of data bus lines, each ofwhich connects the timing controller to each of the N source drive ICsin a point-to-point manner, a lock check line that connects a firstsource drive IC of the N source drive ICs to the timing controller andcascade-connects the N source drive ICs to one another, and a feedbacklock check line that connects a last source drive IC of the N sourcedrive ICs to the timing controller. The timing controller seriallytransfers a preamble signal, in which a plurality of bits having a highlogic level are successively arranged and then a plurality of bitshaving a low logic level are successively arranged, to each of the Nsource drive ICs through each of the N pairs of data bus lines,transfers a lock signal indicating that a phase of an internal clockpulse output from each of the N source drive ICs is locked to the firstsource drive IC through the lock check line, receives a feedback signalof the lock signal from the last source drive IC through the feedbacklock check line, and serially transfers at least one source controlpacket for controlling a data voltage output from each of the N sourcedrive ICs to each of the N source drive ICs through each of the N pairsof data bus lines. A swing width of an output voltage of the timingcontroller including the preamble signal, the lock signal, and thesource control packet increases in proportion to a distance between thetiming controller and the N source drive ICs.

After the timing controller serially transfers the source controlpacket, the timing controller serially transfers at least one RGB datapacket to each of the N source drive ICs through each of the N pairs ofdata bus lines. A swing width of a voltage of the RGB data packetsupplied to the N source drive ICs increases in proportion to thedistance between the timing controller and the N source drive ICs.

The RGB data packet successively includes clock bits, first RGB databits, internal data enable clock bits, and second RGB data bits in theorder named.

Each of the N source drive ICs restores a first reference clock from thepreamble signal to output the first reference clock and a first internalclock pulse whose a phase is locked. If the phases of the first internalclock pulses output from the N source drive ICs are locked, the lastsource drive IC transfers the feedback signal of the lock signal to thetiming controller through the feedback lock check line, and then each ofthe N source drive ICs restores source control data from the sourcecontrol packet. Each of the N source drive ICs restores a secondreference clock from the clock bits included in the RGB data packet,samples RGB data included in the RGB data packet based on the secondreference clock and a second internal clock pulse whose a phase islocked, and converts the RGB data into a positive or negative datavoltage depending on the source control data to output thepositive/negative data voltage.

The source control data includes a polarity control signal determining apolarity of the positive/negative data voltage that is output from eachof the N source drive ICs and is supplied to data lines of a liquidcrystal display panel and a source output enable signal that controls anoutput timing of the positive/negative data voltage output from each ofthe N source drive ICs.

The source control data includes an activation information of the sourceoutput enable signal, a pulse width information of the source outputenable signal, and an activation information of the polarity controlsignal.

A pulse width of the source output enable signal is determined by amultiplication of a length of one of the source control packet and theRGB data packet by “i”, where i is a natural number, depending on thepulse width information of the source output enable signal.

Each of the N source drive ICs outputs a first positive data voltage, asecond positive data voltage, a first negative data voltage, and asecond negative data voltage in the order named. The source outputenable signal includes first pulses for controlling an output timing ofeach of the first positive data voltage and the first negative datavoltage and second pulses for controlling an output timing of each ofthe second positive data voltage and the second negative data voltage. Awidth of the second pulse is greater than a width of the first pulse.

The RGB data packet includes a first RGB data packet to be displayed onodd-numbered lines of a liquid crystal display panel and a second RGBdata packet to be displayed on even-numbered lines of the liquid crystaldisplay panel. An RGB data arrangement order in the first RGB datapacket is different from an RGB data arrangement order in the second RGBdata packet.

The first RGB data packet successively includes R data of a first pixel,G data of the first pixel, and B data of the first pixel in the ordernamed. The second RGB data packet successively includes B data of asecond pixel, R data of a third pixel, and B data of the third pixel inthe order named.

The first RGB data packet further includes clock bits arranged prior tothe R data of the first pixel and internal data enable clock bitsarranged between first G data of the first pixel and second G data ofthe first pixel. The second RGB data packet further includes clock bitsarranged prior to R data of the second pixel and internal data enableclock bits arranged between first R data of the third pixel and second Rdata of the third pixel.

Each of the N source drive ICs adjusts a pulse width of the sourceoutput enable signal by a multiplication of a length of one of thesource control packet and the RGB data packet by “i”, where i is anatural number, depending on the pulse width information of the sourceoutput enable signal.

The timing controller serially transfers at least one second sourcecontrol packet for controlling the data voltage output from each of theN source drive ICs to each of the N source drive ICs through each of theN pairs of data bus lines. The second source control packet includes atleast one of PWRC1/2 option information determining an amplificationratio of an output buffer of each of the N source drive ICs, MODE optioninformation determining an output of a charge share voltage of each ofthe N source drive ICs, SOE_EN option information determining areceiving path of the source output enable signal, PACK_EN optioninformation determining a receiving path of the polarity control signal,CHMODE option information determining the number of output channels ofthe N source drive ICs, CID1/2 option information that gives a chipidentification code to each of the N source drive ICs to independentlycontrol the N source drive ICs, and H_(—)2DOT option informationdetermining a horizontal polarity cycle of the positive/negative datavoltage output from the N source drive ICs.

After the timing controller receives at least one of the feedback signalof the lock signal and a predetermined test mode enable signal, thetiming controller serially transfers the source control packet and theRGB data packet to each of the N source drive ICs through each of the Npairs of data bus lines.

The liquid crystal display further comprises a pair of control linesconnecting in parallel the timing controller to the N source drive ICs.The timing controller transfers a chip identification code forindividually indentifying the N source drive ICs and control datacontrolling functions of each of the N source drive ICs to the N sourcedrive ICs through the pair of control lines.

In another aspect, there is a method of driving a liquid crystal displayincluding a timing controller and N source drive integrated circuits(ICs), where N is an integer equal to or greater than 2, the methodcomprising generating a preamble signal, in which a plurality of bitshaving a high logic level are successively arranged and then a pluralityof bits having a low logic level are successively arranged, from thetiming controller, serially transferring the preamble signal to each ofthe N source drive ICs through each of N pairs of data bus linesconnecting the timing controller to the N source drive ICs in apoint-to-point manner, generating a lock signal indicating that a phaseof an internal clock pulse output from each of the N source drive ICs islocked from the timing controller, transferring the lock signal to afirst source drive IC of the N source drive ICs through a lock checkline that connects the first source drive IC to the timing controllerand cascade-connects the N source drive ICs to one another, generating afeedback signal of the lock signal from a last source drive IC of the Nsource drive ICs, transferring the feedback signal of the lock signal tothe timing controller through a feedback lock check line connecting thelast source drive IC to the timing controller, generating at least onesource control packet for controlling a data voltage output from each ofthe N source drive ICs from the timing controller, and seriallytransferring the source control packet to each of the N source drive ICsthrough each of the N pairs of data bus lines. A swing width of anoutput voltage of the timing controller including the preamble signal,the lock signal, and the source control packet increases in proportionto a distance between the timing controller and the N source drive ICs.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by illustration only, since various changes and modificationswithin the spirit and scope of the invention will become apparent tothose skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a block diagram illustrating a liquid crystal displayaccording to an embodiment of the invention;

FIG. 2 illustrates lines between a timing controller and source driveintegrated circuits (ICs);

FIGS. 3 and 4 are block diagrams illustrating a configuration of asource drive IC;

FIG. 5 is a block diagram illustrating a configuration of a gate driveIC;

FIG. 6 is a flow chart illustrating in stages a signal transfer processbetween a timing controller and source drive ICs;

FIG. 7 is a block diagram illustrating a clock separation and datasampling unit;

FIG. 8 illustrates an example of a serial communication control path anda chip identification code capable of allowing source drive ICs toperform a debugging operation;

FIG. 9 is a block diagram illustrating a phase locked loop (PLL);

FIG. 10 is a waveform diagram illustrating Phase 1 signals generated bya timing controller;

FIG. 11 is a waveform diagram illustrating Phase 2 signals generated bya timing controller;

FIGS. 12 and 13 are waveform diagrams illustrating Phase 3 signalsgenerated by a timing controller;

FIG. 14 illustrates an example of a data mapping table of a sourcecontrol packet and an RGB data packet;

FIG. 15 illustrates an example of a data mapping table of a dummy sourcecontrol packet, a real source control packet, and a last dummy sourcecontrol packet;

FIG. 16 illustrates a first implementation of a real source controlpacket;

FIG. 17 is a waveform diagram illustrating a source output enable signalcontrolled by source output-related control data and a polarity controlsignal controlled by polarity-related control data in a real sourcecontrol packet of FIG. 16;

FIG. 18 illustrates a pulse width of a source output enable signaldetermined depending on SOE_PRD of a real source control packet;

FIG. 19 is a waveform diagram illustrating changes in a pulse width of asource output enable signal depending on SOE_PRD of a real sourcecontrol packet;

FIG. 20 illustrates a second implementation of a real source controlpacket;

FIG. 21 is a waveform diagram illustrating a source output enable signaland a polarity control signal controlled by source output-relatedcontrol data and polarity-related control data in a real source controlpacket of FIG. 20;

FIGS. 22A to 22C illustrate a pulse width of a source output enablesignal controlled depending on source output-related control data of areal source control packet;

FIG. 23 is a waveform illustrating a charge non-uniformity of liquidcrystal cells in a vertical 2-dot inversion manner;

FIG. 24 is a waveform illustrating an example compensating for a chargenon-uniformity of liquid crystal cells through an adjustment of a pulsewidth of a source output enable signal;

FIG. 25 is a waveform illustrating changes in a swing width depending ona distance between a timing controller and a source drive IC;

FIG. 26 illustrates an example of a pixel array;

FIGS. 27A and 27B illustrate an RGB data packet transferred to a pixelarray;

FIG. 28 is a waveform diagram illustrating an output of a clockseparation and data sampling unit;

FIGS. 29A to 29D are cross-sectional views illustrating a lengthconversion of an RGB data packet depending on changes in a bit rate ofthe RGB data packet;

FIGS. 30 and 31 are waveform diagrams illustrating Phase 1 signalsaccording to another embodiment of the invention; and

FIG. 32 illustrates an additional configuration of a liquid crystaldisplay according to embodiments of the invention for a test mode.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail embodiments of the inventionexamples of which are illustrated in the accompanying drawings.

As shown in FIG. 1, a liquid crystal display according to an embodimentof the invention includes a liquid crystal display panel 10, a timingcontroller TCON, a plurality of source drive integrated circuits (ICs)SDIC#1 to SDIC#8, and a plurality of gate drive ICs GDIC#1 to GDIC#4.

The liquid crystal display panel 10 includes an upper glass substrate, alower glass substrate, and a liquid crystal layer between the upper andlower glass substrates. The liquid crystal display panel 10 includes m×nliquid crystal cells Clc arranged at each of crossings of m data linesDL and n gate lines GL in a matrix format.

A pixel array including the data lines DL, the gate lines GL, thin filmtransistors (TFTs), a storage capacitor Cst, etc. is formed on the lowerglass substrate of the liquid crystal display panel 10. Each of theliquid crystal cells Clc is driven by an electric field between a pixelelectrode 1 receiving a data voltage through the TFT and a commonelectrode 2 receiving a common voltage Vcom. In each of the TFTs, a gateelectrode is connected to the gate line GL, a source electrode isconnected to the data line DL, and a drain electrode is connected to thepixel electrode 1 of the liquid crystal cell Clc. The TFT is turned onwhen a gate pulse is supplied through the gate line GL, and thussupplies a positive or negative analog video data voltage receivedthrough the data line DL to the pixel electrode 1 of the liquid crystalcell Clc.

A black matrix, a color filter, the common electrode 2, etc, are formedon the upper glass substrate of the liquid crystal display panel 10.

The common electrode 2 is formed on the upper glass substrate in avertical electric drive manner, such as a twisted nematic (TN) mode anda vertical alignment (VA) mode. The common electrode 2 and the pixelelectrode 1 are formed on the lower glass substrate in a horizontalelectric drive manner, such as an in-plane switching (IPS) mode and afringe field switching (FFS) mode.

Polarizing plates are respectively attached to the upper and lower glasssubstrates of the liquid crystal display panel 10. Alignment layers forsetting a pre-tilt angle are respectively formed on the upper and lowerglass substrates. A spacer is formed between the upper and lower glasssubstrates to keep cell gaps of the liquid crystal cells Clc constant.

The liquid crystal display according to the embodiment of the inventionmay be embodied in any liquid crystal mode as well as the TN, VA, IPS,and FFS modes. Further, the liquid crystal display according to theembodiment of the invention may be implemented as any type liquidcrystal display including a backlit liquid crystal display, atransflective liquid crystal display, and a reflective liquid crystaldisplay.

The timing controller TCON receives an external timing signal such as,vertical and horizontal sync signals Vsync and Hsync, an external dataenable signal DE, and a dot clock CLK through an interface, such as alow voltage differential signaling (LVDS) interface and a transitionminimized differential signaling (TMDS) interface to generate timingcontrol signals for controlling operation timings of the source driveICs SDIC#1 to SDIC#8 and operation timings of the gate drive ICs GDIC#1to GDIC#4. The timing control signals include a gate timing controlsignal for controlling the operation timings of the gate drive ICsGDIC#1 to GDIC#4 and a source timing control signal for controlling theoperation timings of the source drive ICs SDIC#1 to SDIC#8.

The timing controller TCON is connected to the source drive ICs SDIC#1to SDIC#8 in a point-to-point manner. The timing controller TCONtransfers a preamble signal for initializing the source drive ICs SDIC#1to SDIC#8, a source control data including the source timing controlsignal, a clock, RGB digital video data, etc. to each of the sourcedrive ICs SDIC#1 to SDIC#8 through each of a plurality of pairs of databus lines.

The gate timing control signal includes a gate start pulse GSP, a gateshift clock GSC, a gate output enable signal GOE, and the like. The gatestart pulse GSP is applied to the first gate drive IC GDIC#1 to therebyindicate scan start time of a scan operation so that the first gatedrive IC GDIC#1 generates a first gate pulse. The gate shift clock GSCis a clock for shifting the gate start pulse GSP. A shift register ofeach of the gate drive ICs GDIC#1 to GDIC#4 shifts the gate start pulseGSP at a rising edge of the gate shift clock GSC. The second to fourthgate drive ICs GDIC#2 to GDIC#4 receive a carry signal of the first gatedrive IC GDIC#1 as a gate start pulse to start operating. The gateoutput enable signal GOE controls output timings of the gate drive ICsGDIC#1 to GDIC#4. The gate drive ICs GDIC#1 to GDIC#4 output a gatepulse in a low logic level state of the gate output enable signal GOE,i.e., during a period of time ranging from immediately after a fallingedge of a current pulse to immediately before a rising edge of a nextpulse. 1 cycle of the gate output enable signal GOE is about 1horizontal period.

The source timing control signal is transferred to the source drive ICsSDIC#1 to SDIC#8 through the pair of data bus lines for a predeterminedtime interval between a transfer time of the preamble signal and atransfer time of the RGB digital video data. The source timing controlsignal includes polarity-related control data, source output-relatedcontrol data, etc. The polarity-related control data includes a controlinformation for controlling a polarity control signal POL of pulse formgenerated inside the source drive ICs SDIC#1 to SDIC#8. Adigital-to-analog convertor (DAC) of each of the source drive ICs SDIC#1to SDIC#8 converts the RGB digital video data into an positive ornegative analog video data voltage in response to the polarity controlsignal POL. The source output-related control data includes a controlinformation for controlling a source output enable signal SOE of pulseform generated inside the source drive ICs SDIC#1 to SDIC#8. The sourceoutput enable signal SOE controls an output timing of thepositive/negative analog video data voltage from the source drive ICsSDIC#1 to SDIC#8.

Each of the gate drive ICs GDIC#1 to GDIC#4 sequentially supplies thegate pulse to the gate lines GL in response to the gate timing controlsignal.

Each of the source drive ICs SDIC#1 to SDIC#8 locks a frequency and aphase of an internal clock pulse output from a clock separation and datasampling unit embedded inside each of the source drive ICs SDIC#1 toSDIC#8 depending on the preamble signal transferred from the timingcontroller TCON through the pair of data bus lines. Then, each of thesource drive ICs SDIC#1 to SDIC#8 restores a clock from a source controlpacket input as a digital bit stream through the pair of data bus linesto generate a serial clock. Subsequently, each of the source drive ICsSDIC#1 to SDIC#8 samples the polarity-related control data and thesource output-related control data. Each of the source drive ICs SDIC#1to SDIC#8 outputs the polarity control signal POL and the source outputenable signal SOE using the polarity-related control data and the sourceoutput-related control data.

After each of the source drive ICs SDIC#1 to SDIC#8 restores a clockfrom a source control packet input as a digital bit stream through thepair of data bus lines to restore the polarity control signal POL andthe source output enable signal SOE, each of the source drive ICs SDIC#1to SDIC#8 restores a clock from an RGB data packet input as a digitalbit stream through the pair of data bus lines to generate a serial clockfor data sampling. Further, each of the source drive ICs SDIC#1 toSDIC#8 samples RGB digital video data serially input depending on theserial clock. Each of the source drive ICs SDIC#1 to SDIC#8 deserializesthe sequentially sampled RGB digital video data to output RGB paralleldata. Then, each of the source drive ICs SDIC#1 to SDIC#8 converts theRGB parallel data into the positive/negative analog video data voltagein response to the polarity control signal POL to supply thepositive/negative analog video data voltage to the data lines DL inresponse to the source output enable signal SOE.

FIG. 2 illustrates lines between the timing controller TCON and thesource drive ICs SDIC#1 to SDIC#8.

As shown in FIG. 2, a plurality of pairs of data bus lines DATA&CLK,first and second pairs of control lines SCL/SDA1 and SCL/SDA2, lockcheck lines LCS1 and LCS2, etc. are formed between the timing controllerTCON and the source drive ICs SDIC#1 to SDIC#8.

The timing controller TCON sequentially transfers the preamble signal,the source control packet, and the RGB data packet to each of the sourcedrive ICs SDIC#1 to SDIC#8 through each of the pairs of data bus linesDATA&CLK. The source control packet is a bit stream including clockbits, polarity-related control data bits, source output-related controldata bits, etc. The RGB data packet is a bit stream including clockbits, internal data enable clock bits, RGB data bits, etc. Each of thepairs of data bus lines DATA&CLK connects in series the timingcontroller TCON to each of the source drive ICs SDIC#1 to SDIC#8.Namely, the timing controller TCON is connected to the source drive ICsSDIC#1 to SDIC#8 in the point-to-point manner. Each of the source driveICs SDIC#1 to SDIC#8 restores clocks input through the pair of data buslines DATA&CLK. Accordingly, lines for transferring a clock carry andthe RGB video data are not necessary between the adjacent source driveICs SDIC#1 to SDIC#8.

The timing controller TCON transfers a chip identification code CID ofeach of the source drive ICs SDIC#1 to SDIC#8 and chip individualcontrol data for controlling functions of each of the source drive ICsSDIC#1 to SDIC#8 to each of the source drive ICs SDIC#1 to SDIC#8through the pairs of control lines SCL/SDA1 and SCL/SDA2. The pairs ofcontrol lines SCL/SDA1 and SCL/SDA2 are commonly connected between thetiming controller TCON and the source drive ICs SDIC#1 to SDIC#8. Morespecifically, as shown in FIG. 8, if the source drive ICs SDIC#1 toSDIC#8 are divided into two groups and the two groups are respectivelyconnected to printed circuit boards (PCBs) PCB1 and PCB2, the first pairof control lines SCL/SDA1 on the left connect in parallel the timingcontroller TCON to the first to fourth source drive ICs SDIC#1 toSDIC#4, and the second pair of control lines SCL/SDA2 on the rightconnect in parallel the timing controller TCON to the fifth to eighthsource drive ICs SDIC#5 to SDIC#8.

The timing controller TCON supplies a lock signal LOCK, that confirmswhether or not a phase and a frequency of the internal clock pulseoutput from the clock separation and data sampling unit of each of thesource drive ICs SDIC#1 to SDIC#8 is stably locked, to the first sourcedrive IC SDIC#1 through a lock check line LCS1. The source drive ICsSDIC#1 to SDIC#8 are cascade-connected to one another through the lockcheck line LCS1. If a frequency and a phase of an internal clock pulseoutput from the first source drive IC SDIC#1 are locked, the firstsource drive IC SDIC#1 transfers the lock signal LOCK of a high logiclevel to the second source drive IC SDIC#2. Next, after a frequency anda phase of an internal clock pulse output from the second source driveIC SDIC#2 are locked, the second source drive IC SDIC#2 transfers thelock signal LOCK of a high logic level to the third source drive ICSDIC#3. The above-described locking operation is sequentially performed,and finally, after a frequency and a phase of an internal clock pulseoutput from the last source drive IC SDIC# are locked, the last sourcedrive IC SDIC#8 feedback-inputs the lock signal LOCK of a high logiclevel to the timing controller TCON through a feedback lock check lineLCS2. Only after the timing controller TCON receives a feedback signalof the lock signal LOCK, the timing controller TCON transfers the RGBdata packets to the source drive ICs SDIC#1 to SDIC#8.

FIG. 3 is a block diagram illustrating a configuration of the sourcedrive ICs SDIC#1 to SDIC#8.

As shown in FIG. 3, each of the source drive ICs SDIC#1 to SDIC#8supplies the positive/negative analog video data voltage to the k datalines D1 to Dk (where k is a positive integer less than m). Each of thesource drive ICs SDIC#1 to SDIC#8 includes a clock separation and datasampling unit 21, a digital-to-analog converter (DAC) 22, an outputcircuit 23, etc.

In Phase 1, the clock separation and data sampling unit 21 locks thephase and the frequency of the internal clock pulse depending on thepreamble signal input at a low frequency through the pair of data buslines DATA&CLK. Subsequently, in Phase 2, the clock separation and datasampling unit 21 restores a reference clock from the source controlpacket input as a bit stream through the pair of data bus lines DATA&CLKand separates the polarity-related control data from the reference clockto thereby restore the polarity control signal POL based on thepolarity-related control data. Further, the clock separation and datasampling unit 21 separates the source output-related control data fromthe source control packet to restore the source output enable signal SOEbased on the source output-related control data.

Subsequently, in Phase 3, the clock separation and data sampling unit 21separates a clock from the RGB data packet input through the pair ofdata bus lines DATA&CLK to restore a reference clock. Further, the clockseparation and data sampling unit 21 generates serial clock signals forsampling each of RGB digital video data bits depending on the referenceclock. For this, the clock separation and data sampling unit 21 includesa phase locked circuit capable of outputting internal clock pulseshaving a stable phase and a stable frequency. Examples of the phaselocked circuit include a phase locked loop (PLL) and a delay locked loop(DLL). In the embodiment, an example of using a PLL circuit as the phaselocked circuit will be described later. In the embodiment, the clockseparation and data sampling unit 21 may include the DLL as well as thePLL. FIGS. 7 to 9 illustrate an example of embodying the clockseparation and data sampling unit 21 using the PLL. However, the clockseparation and data sampling unit 21 may be embodied using the DLL.

The clock separation and data sampling unit 21 samples and latches eachof the RGB data bits serially input through the pair of data bus linesDATA&CLK depending on the serial clock and then simultaneously outputsthe latched RGB data. Namely, the clock separation and data samplingunit 21 converts serial data into RGB parallel data.

The DAC 22 converts the RGB digital video data from the clock separationand data sampling unit 21 into a positive gamma compensation voltage GHor a negative gamma compensation voltage GL in response to the polaritycontrol signal POL and then converts the positive gamma compensationvoltage GH or the negative gamma compensation voltage GL into a positiveor negative analog video data voltage. For the above-describedoperation, as shown in FIG. 4, the DAC 22 includes a P-decoder (PDEC) 41receiving the positive gamma compensation voltage GH, an N-decoder(NDEC) 42 receiving the negative gamma compensation voltage GL, and amultiplexer 43 selecting an output of the P-decoder 41 and an output ofthe N-decoder 42 in response to the polarity control signal POL. TheP-decoder 41 decodes RGB digital video data input from the clockseparation and data sampling unit 21 to output the positive gammacompensation voltage GH corresponding to a gray level of the RGB digitalvideo data. The N-decoder 42 decodes RGB digital video data input fromthe clock separation and data sampling unit 21 to output the negativegamma compensation voltage GL corresponding to a gray level of the RGBdigital video data. The multiplexer 43 alternately selects the positivegamma compensation voltage GH and the negative gamma compensationvoltage GL in response to the polarity control signal POL and outputsthe positive or negative analog video data voltage as the selectedpositive or negative gamma compensation voltage GH or GL.

The output circuit 23 supplies a charge share voltage or the commonvoltage Vcom to the data lines D1 to Dk through an output buffer duringa high logic level period of the source output enable signal SOE. Theoutput circuit 23 supplies the positive/negative analog video datavoltage to the data lines D1 to Dk through the output buffer during alow logic level period of the source output enable signal SOE. Thecharge share voltage is generated when the data line receiving thepositive analog video data voltage and the data line receiving thenegative analog video data voltage are short-circuited. The charge sharevoltage has an average voltage level between the positive analog videodata voltage and the negative analog video data voltage.

FIG. 5 is a block diagram illustrating a configuration of the gate driveICs GDIC#1 to GDIC#4.

As shown in FIG. 5, each of the gate drive ICs GDIC#1 to GDIC#4 includesa shift register 50, a level shifter 52, a plurality of AND gates 51connected between the shift register 50 and the level shifter 52, and aninverter 53 for inverting the gate output enable signal GOE.

The shift register 50 includes a plurality of cascade connected Dflip-flops and sequentially shifts the gate start pulse GSP in responseto the gate shift clock GSC using the cascade connected D flip-flops.Each of the AND gates 51 performs an AND operation on an output signalof the shift register 50 and an inversion signal of the gate outputenable signal GOE to obtain an output. The inverter 53 inverts the gateoutput enable signal GOE and supplies the inversion signal of the gateoutput enable signal GOE to the AND gates 51. Accordingly, each of thegate drive ICs GDIC#1 to GDIC#4 outputs the gate pulse when the gateoutput enable signal GOE is in a low logic level state.

The level shifter 52 shifts a swing width of an output voltage of theAND gate 51 to a swing width suitable to drive the TFTs in the pixelarray of the liquid crystal display panel 10. An output signal of thelevel shifter 52 is sequentially supplied to the gate lines G1 to Gk.

The shift register 50 together with the TFTs of the pixel array may bedirectly formed on the glass substrate of the liquid crystal displaypanel 10. In this case, the level shifter 52 may be formed on not theglass substrate of the liquid crystal display panel 10 but a controlboard or a source PCB together with the timing controller TCON, a gammavoltage generating circuit, etc.

FIG. 6 is a flow chart illustrating in stages a signal transfer processbetween the timing controller TCON and the source drive ICs SDIC#1 toSDIC#8.

As shown in FIG. 6, if a power is applied to the liquid crystal display,the timing controller TCON supplies Phase 1 signals to each of thesource drive ICs SDIC#1 to SDIC#8 through each of the pairs of data buslines DATA&CLK in steps S1 and S2. The Phase 1 signals include thepreamble signal of a low frequency and a lock signal supplied to thefirst source drive IC SDIC#1.

The clock separation and data sampling unit 21 of the first source driveIC SDIC#1 restores the preamble signal to a PLL reference clock andtransfers a lock signal of a high logic level to the second source driveIC SDIC#2 when a phase of the PLL reference clock and a phase of aninternal clock pulse output from the PLL of the first source drive ICSDIC#1 are locked, in steps S3 to S5. Subsequently, when internal clockpulses output from the clock separation and data sampling units 21 ofthe second to eighth source drive ICs SDIC#2 to SDIC#8 are sequentiallylocked stably, the eighth source drive IC SDIC#8 feedback inputs a locksignal of a high logic level to the timing controller TCON in steps S6and S7.

If the timing controller TCON receives the lock signal of the high logiclevel from the eighth source drive IC SDIC#8, the timing controller TCONdecides that a phase and a frequency of the internal clock pulse outputfrom the clock separation and data sampling unit 21 of each of all thesource drive ICs SDIC#1 to SDIC#8 are stably locked. Thus, the timingcontroller TCON supplies Phase 2 signals to the source drive ICs SDIC#1to SDIC#8 through the pairs of data bus lines DATA&CLK in thepoint-to-point manner in step S8. The Phase 2 signals include aplurality of source control packets including polarity-related controldata bits and source output-related control data bits.

Following the Phase 2 signals, the timing controller TCON supplies Phase3 signals to the source drive ICs SDIC#1 to SDIC#8 in the point-to-pointmanner in step S10. The Phase 3 signals include a plurality of RGB datapackets to which the liquid crystal cells on 1 line of the liquidcrystal display panel 10 will be charged during 1 horizontal period.

The PLL output of the clock separation and data sampling unit 21 of eachof the source drive ICs SDIC#1 to SDIC#8 may be unlocked during anoutput transfer process of the Phase 2 signals or the Phase 3 signals.Namely, the phase and the frequency of the internal clock pulse outputfrom the PLL of the clock separation and data sampling unit 21 may beunlocked. More specifically, when the timing controller TCON receivesthe feedback signal of the lock signal inverted at a low logic level,the timing controller TCON decides that the internal clock pulses outputfrom the PLL of the clock separation and data sampling unit 21 areunlocked, in step S9 and S11. Thus, the timing controller TCON transfersthe Phase 1 signals to the source drive ICs SDIC#1 to SDIC#8.Subsequently, after, the phase and the frequency of the internal clockpulse output from the PLL of each of the source drive ICs SDIC#1 to arelocked, the timing controller TCON again starts performing the outputtransfer process of the Phase 2 signals and the Phase 3 signals.

FIG. 7 is a block diagram illustrating the clock separation and datasampling unit 21 of each of the source drive ICs SDIC#1 to SDIC#8.

As shown in FIG. 7, the clock separation and data sampling unit 21includes an on-die terminator (ODT) 61, an analog delay replica (ADR)62, a clock separator 63, a PLL 64, a PLL lock detector 65, a tunableanalog delay 66, a deserializer 67, a digital filter 68, a phasedetector 69, a lock detector 70, an I²C controller 71, a power-on reset(POR) 72, an AND gate 73, and an SOE&POL restoring unit 74.

The ODT 61 includes a termination resistor embedded inside the ODT 61 toimprove signal integrity by removing a noise mixed in the preamblesignal, the source control packet, and the RGB data packet receivedthrough the pairs of data bus lines DATA&CLK. Further, the ODT 61includes a receiving buffer and an equalizer embedded inside the ODT 61to amplify an input differential signal and to convert the amplifieddifferential signal into digital data. The ADR 62 delays the RGB dataand the clock received from the ODT 61 by a delay value of the tunableanalog delay 66 to allow a delay value of a clock path to be equal to adelay value of a data path.

The clock separator 63 separates clock bits from the source controlpacket and the RGB data packet restored by the ODT 61 to restore theclock bits to a reference clock of the PLL 64. The clock bits includeclock bits, dummy clock bits, internal data enable clock bits, etc. ThePLL 64 generates clocks for sampling bits of the source control packetand bits of the RGB data packet. If the RGB data packet includes 10-bitRGB data and 4-bit clocks are assigned between the 10-bit RGB data, thePLL 64 generates 34 internal clock pulses per 1 RGB data packet. The PLLlock detector 65 checks a phase and a frequency of each of the internalclock pulses output from the PLL 64 in conformity with a predetermineddata rate to detect whether or not the internal clock pulses are locked.

The tunable analog delay 66 compensates for a slight phase differencebetween the RGB digital data received from the ODT 61 and restoredclocks feedback-input via the phase detector 69 and the digital filter68, so that data can be sampled in the center of the clock. Thedeserializer 67 includes a plurality of flip-flops embedded inside thedeserializer 67 to sample and latch the RGB digital video data bitsserially input based on internal serial clock pulses serially outputfrom the PLL 64. Then, the deserializer 67 simultaneously outputs thelatched RGB digital video to thereby output RGB parallel data.

The digital filter 68 and the phase detector 69 receive the sampled RGBdigital video data and determine a delay value of the tunable analogdelay 66. The lock detector 70 compares the RGB parallel data restoredby the deserializer 67 with an output PLL_LOCK of the PLL lock detector65 to check an error amount of data enable clocks of the RGB paralleldata. If the error amount is equal to or greater than a predeterminedvalue, a physical interface (PHY) circuit entirely operates again byunlocking the internal clock pulses output from the PLL 64. The lockdetector 70 generates an output of a low logic level when the internalclock pulses output from the PLL 64 are unlocked. On the other hand, thelock detector 70 generates an output of a high logic level when theinternal clock pulses output from the PLL 64 are locked. The AND gate 73performs an AND operation on a lock signal “Lock In” received from thetiming controller TCON or a lock signal “Lock In” transferred by thesource drive ICs SDIC#1 to SDIC#7 in previous stage and an output of thelock detector 70. Then, the AND gate 73 outputs a lock signal “Lock Out”of a high logic level when the lock signal “Lock In” and the output ofthe lock detector 70 are in a high logic level state. The lock signal“Lock Out” of the high logic level is transferred to the source driveICs SDIC#2 to SDIC#8 in next stage, and the last source drive IC SDIC#8inputs the lock signal “Lock Out” to the timing controller TCON.

The POR 72 generates a reset signal RESETB for initializing the clockseparation and data sampling unit 21 depending on a previously set powersequence and generates a clock of about 50 MHz to supply the clock todigital circuits including the above circuits.

The I²C controller 71 controls an operation of each of the above circuitblocks using the chip identification code CID input as serial datathrough the pair of control lines SCL/SDA and the chip individualcontrol data. The chip identification codes CID each having a differentlogic level are respectively given to the source drive ICs SDIC#1 toSDIC#8 as shown in FIG. 8, so that the source drive ICs SDIC#1 to SDIC#8can be individually controlled. The I²C controller 71 may perform PLLpower down, buffer power down of the ODT 61, EQ On/Off operation of theODT 61, a control of a charge bump current of the PLL 64, a control ofVCO range manual selection of the PLL 64, PLL lock signal push throughI²C communication, an adjustment of an analog delay control value,disable of the lock detector 70, a change in a coefficient of thedigital filter 68, a change function in a coefficient of the digitalfilter 68, physical interface (PHY)_RESETB signal push through I²C, anoperation of substituting the lock signal of the previous source driveICs SDIC#1 to SDIC#7 with a reset signal of the current source drive ICsSDIC#1 to SDIC#8, setting of a vertical resolution of an input image, astorage of a history about data enable clock transition for analyzing ageneration cause of the physical interface (PHY)_RESETB signal, etcdepending on the chip individual control data input from the timingcontroller TCON through serial data bus SDA of the pair of control linesSCL/SDA.

The SOE&POL restoring unit 74 samples the polarity-related control dataof the source control packet from the ODT 61 in response to the internalclock pulses output from the PLL 64 to generate the polarity controlsignal POL of a high logic level (or a low logic level). Then, theSOE&POL restoring unit 74 inverts a logic level of the polarity controlsignal POL every i horizontal periods (where, “i” is a natural number).The SOE&POL restoring unit 74 samples the source output-related controldata of the source control packet from the ODT 61 in response to theinternal clock pulses output from the PLL 64. Then, the SOE&POLrestoring unit 74 generates the source output enable signal SOEdepending on the source output-related control data using methodsillustrated in FIGS. 16 to 22C and adjusts a pulse width of the sourceoutput enable signal SOE.

FIG. 9 is a block diagram illustrating the PLL 64.

As shown in FIG. 9, the PLL 64 includes a phase comparator 92, a chargepump 93, a loop filter 94, a pulse-to-voltage converter 95, a voltagecontrolled oscillator (VCO) 96, and a digital controller 97.

The phase comparator 92 compares a phase of a reference clock REF_clkreceived from the clock separator 63 with a phase of a feedback edgeclock FB_clk received from a clock separator replica (CSR) 91. The phasecomparator 92 has a pulse width corresponding to a phase differencebetween the reference clock REF_clk and the feedback edge clock FB_clkas a comparison result. When the phase of the reference clock REF_clk isearlier than the phase of the feedback edge clock FB_clk, the phasecomparator 92 outputs a positive pulse. On the other hand, when thephase of the reference clock REF_clk is later than the phase of thefeedback edge clock FB_clk, the phase comparator 92 outputs a negativepulse.

The charge pump 93 controls an amount of charges supplied to the loopfilter 94 depending on a width and a polarity of an output pulse of thephase comparator 92. The loop filter 94 accumulates or discharges thecharges depending on the amount of charges controlled by the charge pump93 and removes a high frequency noise including a harmonic component ina clock input to the pulse-to-voltage converter 95.

The pulse-to-voltage converter 95 converts a pulse received from theloop filter 94 into a control voltage of the VCO 96 and controls a levelof the control voltage of the VCO 96 depending on a width and a polarityof the pulse received from the loop filter 94. When a bit stream of 1RGB data packet includes 10-bit RGB data and 4 clock bits, the VCO 96generates 34 edge clocks and 34 center clocks per the 1 RGB data packet.Further, the VCO 96 controls a phase delay amount of clocks depending onthe control voltage from the pulse-to-voltage converter 95 and dependingon control data from the digital controller 97.

A first edge clock EG[0] output from the VCO 96 is a feedback edge clockand is input to the clock separator replica 91. The feedback edge clockEG[0] has a frequency corresponding to 1/34 of an output frequency ofthe VCO 96. The digital controller 97 receives the reference clockREF_clk from the clock separator 63 and the feedback edge clock FB_clkfrom the clock separator replica 91 and compares a phase of thereference clock REF_clk with a phase of the feedback edge clock FB_clk.Further, the digital controller 97 compares a phase difference obtainedas a comparison result with a phase of a 50-MHz clock signal clk_oscfrom the POR 72. The digital controller 97 controls an output delayamount of the VCO 96 depending on a comparison result of a phasedifference to select an oscillation area of the VCO 96.

FIG. 10 is a waveform diagram illustrating signals generated by thetiming controller TCON in Phase 1.

As shown in FIG. 10, in Phase 1, the timing controller TCON generates alock signal and a preamble signal of a low frequency. In the preamblesignal of the low frequency, a plurality of bits having a high logiclevel are successively arranged, and then a plurality of bits having alow logic level are successively arranged. A frequency of the preamblesignal corresponds to 1/34 of a frequency of the internal clock pulseoutput from the PLL 64 of the clock separation and data sampling unit 21when a bit stream of 1 RGB data packet includes 10-bit RGB data and 4clock bits. The clock separator 63 of the clock separation and datasampling unit 21 transitions the reference clock REF_clk to a high logiclevel in synchronization with bits of the preamble signal of a highlogic level and transitions the reference clock REF_clk to a low logiclevel in synchronization with bits of the preamble signal of a low logiclevel.

The clock separation and data sampling unit 21 of each of the sourcedrive ICs SDIC#1 to SDIC#8 repeatedly performs an operation of comparingthe phase of the reference clock REF_clk generated depending on thepreamble signal with the phase of the feedback edge clock FB_clk andlocking the internal clock pulses. If the internal clock pulses arestably locked, the lock signal is transferred to the source drive ICsSDIC#1 to SDIC#8 in next stage.

In an initial power-on phase of the liquid crystal display, the timingcontroller TCON receives the lock signal from the last source drive ICSDIS#8 to confirm that a phase and a frequency of the internal clockpulses serially output from the clock separation and data sampling unit21 are locked. Then, the timing controller TCON outputs the Phase 2signals during a blanking period of the vertical sync signal Vsync.

FIG. 11 is a waveform diagram illustrating signals generated by thetiming controller TCON in Phase 2.

As shown in FIG. 11, in Phase 2, the timing controller TCON successivelytransfers a plurality of front dummy source control packets Cf, at leastone real source control packet Cr, a plurality of back dummy sourcecontrol packets Cb and Cl in the order named to each of the source driveICs SDIC#1 to SDIC#8 through the pair of data bus lines DATA&CLK duringa blanking period, in which there is no data, in 1 cycle (i.e., 1horizontal period) of the horizontal sync signal Hsync.

The plurality of front dummy source control packets Cf are successivelytransferred to the source drive ICs SDIC#1 to SDIC#8 prior to the realsource control packet Cr, so that the clock separation and data samplingunit 21 stably receives the real source control packet Cr. The realsource control packet Cr includes polarity-related control data bits andsource output-related control data bits for controlling a polarityinversion operation and a data output of the source drive ICs SDIC#1 toSDIC#8. The plurality of back dummy source control packets Cb and Clsubsequent to the real source control packet Cr are successivelytransferred to the source drive ICs SDIC#1 to SDIC#8, so that the clockseparation and data sampling unit 21 performs a receiving confirmingoperation of the real source control packet Cr and stably receives thePhase 3 signals. A bit value indicating that the Phase 3 signals aretransferred subsequent to a last dummy source control packet Cl of theback dummy source control packets Cb and Cl is assigned to the lastdummy source control packet Cl. Because the source drive ICs SDIC#1 toSDIC#8 read the bit value of the last dummy source control packet Cl andthus can previously know an input of the RGB data packet subsequent tothe last dummy source control packet Cl, the source drive ICs SDIC#1 toSDIC#8 can stably perform an RGB data sampling operation.

The front dummy source control packets Cf, the real source controlpacket Cr, and the back dummy source control packets Cb and Cl may bedistinguished from one another by predetermined bit values as shown in adata mapping table of FIG. 15. Accordingly, the SOE&POL restoring unit74 of the clock separation and data sampling unit 21 distinguishes thesource control packets Cf, Cr, Cb, and Cl from one another bypredetermined bit values. Thus, the SOE&POL restoring unit 74 maydiscriminate between the polarity-related control data and the sourceoutput-related control data of the real source control packet Cr.

The clock separation and data sampling unit 21 of each of the sourcedrive ICs to SDIC#8 separates clocks from the source control packets Cf,Cr, Cb, and Cl to restore a reference clock and compares a phase of thereference clock with a phase of internal clock pulses of a highfrequency to serially output the internal clock pulses for sampling thepolarity-related control data bits and the source output-related controldata bits. Further, the clock separation and data sampling unit 21generates the polarity control signal POL depending on the sampledpolarity-related control data and generates the source output enablesignal SOE depending on the sampled source output-related control data.

As shown in FIG. 11, an RGB data packet is transferred subsequent to theplurality of source control packets Cf, Cr, Cb, and Cl during 1horizontal period, and then a plurality of source control packets may beadditionally transferred subsequent to the RGB data packet. The sourcecontrol packets additionally transferred subsequent to the RGB datapacket may include at least one real source control packet and aplurality of dummy source control packets, and the real source controlpacket may affect an RGB data packet of a next horizontal period.

FIGS. 12 and 13 are waveform diagrams illustrating signals generated bythe timing controller TCON in Phase 3.

As shown in FIGS. 12 and 13, following the Phase 2 signals, the timingcontroller TCON transfers Phase 3 signals (i.e., a plurality of RGB datapackets to be displayed on 1 line of the liquid crystal display) to eachof the source drive ICs SDIC#1 to SDIC#8 through the pair of data buslines DATA&CLK during 1 horizontal period.

More specifically, the clock separation and data sampling unit 21separates a clock CLK and an internal data enable clock DE from the RGBdata packet to restore a reference clock. Then, the clock separation anddata sampling unit 21 compares a phase of the reference clock with aphase of internal clock pulses of a high frequency to serially outputthe internal clock pulses for sampling each of the RGB digital videodata bits. If a bit stream of 1 RGB data packet includes 10-bit RGB dataand 4 clock bits, bits of a dummy clock DUM of a low logic level, bitsof a clock CLK of a high logic level, bits R1 to R10, bits G1 to G5,bits of a dummy data enable clock DE DUM of a low logic level, bits ofan internal data enable clock DE of a high logic level, bits G6 to G10,and bits B1 to B10 are successively assigned to the 1 RGB data packet inthe order named. The clock separation and data sampling unit 21 detectsthe clock CLK and the internal data enable clock DE and thus may decidedata serially input subsequent to the clock CLK and the internal dataenable clock DE as the RGB digital video data. Further, the clockseparation and data sampling unit 21 samples the RGB digital video datadepending on sampling clock.

The clock separation and data sampling unit 21 sets bit values of thedummy data enable clock DE DUM and the data enable clock DE in each ofthe Phase 1 signal and the Phase 2 signal at different bit values frombit values of the dummy data enable clock DE DUM and the data enableclock DE in the Phase 3 signal. Thus, the clock separation and datasampling unit 21 reads the bit values of the dummy data enable clock DEDUM and the data enable clock DE in Phase 3 to sample the RGB data innot Phase 1 and Phase 2 but Phase 3.

The clock separator 63 of the clock separation and data sampling unit 21generates a reference clock REF_clk, whose a rising edge is synchronizedwith the clock CLK and the internal data enable clock DE. Because thereference clock REF_clk is again transitioned in response to theinternal data enable clock DE, a frequency of the reference clockREF_clk in Phase 3 may be two times a frequency of the reference clockREF restored in Phase 1 and Phase 2. As above, if the frequency of thereference clock REF_clk of the clock separation and data sampling unit21 increases, an output of the PLL 64 can be further stabilized becausethe number of stages inside the VCO of the PLL 64 may decrease. Morespecifically, if the reference clock REF_clk of the PLL 64 transitionsin the middle of the RGB data packet in response to the internal dataenable clock DE to increase the frequency of the reference clock REF_clkof the PLL 64 by two times, the number of stages inside the VCO of thePLL 64 may decrease to ½. If the internal data enable clock DE does notuse the reference clock REF_clk as a transition clock, 34 VCO stages arenecessary. On the other hand, if the internal data enable clock DE usesthe reference clock REF_clk as a transition clock, 17 VCO stages arenecessary. If the number of VCO stages in the PLL 64 increases, aneffect resulting from changes in a process, a voltage, and a temperaturePVT is represented by a multiplication of an increase width in thenumber of VCO stages. Therefore, the locking of the PLL 64 may bereleased because of such an external change. Accordingly, the embodimentof the invention uses the internal data enable clock DE in addition tothe clock CLK as the transition clock and thus can increase thefrequency of the reference clock REF_clk of the PLL. Hence, lockingreliability of the PLL 64 can be improved.

The RGB data packet and the source control packets Cf, Cr, Cb, and Clmay be distinguished from each other by setting predetermined bit valuesdifferently from each other. FIG. 14 illustrates a data mapping table ofthe source control packets Cf, Cr, Cb, and Cl generated in Phase 2 andthe RGB data packet generated in Phase 3. However, the data mappingtable according to the embodiment of the invention is not limited to thedata mapping table shown in FIG. 14 and may be variously modified basedon the data mapping table shown in FIG. 14.

As shown in FIG. 14, if each of R data, G data, and B data is 10-bitdata, the RGB data packet includes a total of 34-bit. More specifically,the RGB data packet includes 1-bit clock, 10-bit R data [0:9], 5-bit Gdata [0:4], 1-bit dummy enable clock DE DUM, 1-bit data enable clock DE,5-bit G data [5:9], and 10-bit B data [0:9]. The source control packetsCf, Cr, and Cb have a data length (i.e., 34-bit) equal to a data lengthof the RGB data packet. More specifically, each of the source controlpackets Cf, Cr, and Cb includes 1-bit clock, 15-bit first control datareplacing R data [0:9] and G data [0:4], 1-bit dummy data enable clockDE DUM, 1-bit data enable clock DE, and 15-bit second control datareplacing G data [5:9] and B data [0:9]. The RGB data packet and thesource control packets Cf, Cr, and Cb may be distinguished from eachother by setting a bit value of the dummy data enable clock DE DUM and abit value of the data enable clock DE differently from each other.

The dummy source control packets Cf, Cb, and Cl and the real sourcecontrol packet Cr may be distinguished from each other by predeterminedbits determined by the first control data and the second control data ofFIG. 14. FIG. 15 illustrates an example of a data mapping table of thesource control packets. However, the data mapping table according to theembodiment of the invention is not limited to the data mapping tableshown in FIG. 15 and may be variously modified based on the data mappingtable shown in FIG. 15.

FIG. 15 illustrates a data mapping table of the source control packetsCf, Cr, Cb, and Cl.

As shown in FIG. 15, in the dummy source control packets Cf, Cb, and Cl,a high logic level H, a low logic level L, a low logic level L, and alow logic level L are respectively assigned to 4 bits C0 to C3. On theother hand, in the real source control packet Cr, a high logic level H,a high logic level H, a high logic level H, and a low logic level L arerespectively assigned to 4 bits C0 to C3. Accordingly, the dummy sourcecontrol packets Cf, Cb, and Cl and the real source control packet Cr maybe distinguished by bit values of C1 and C2.

The last dummy source control packet Cl indicating a transfer of the RGBdata packet may be distinguished from the dummy source control packetsCf and Cb by 2 bits C16 and C17. The clock separation and data samplingunit 21 of each of the source drive ICs SDIC#1 to SDIC#8 reads 2 bitsC16 and C17 of the last dummy source control packet Cl and thus maypredict that the RGB data packet will be input subsequent to the lastdummy source control packet Cl. More specifically, first identificationinformations C1 and C2 and second identification informations C16 andC17 are encoded to each of the dummy source control packets Cf, Cb, andCl and the real source control packet Cr. A logic level of firstidentification informations C1 and C2 encoded to the real source controlpacket Cr is set to be different from a logic level of firstidentification informations C1 and C2 encoded to each of the dummysource control packets Cf, Cb, and Cl. Further, a logic level of secondidentification informations C16 and C17 encoded to the last dummy sourcecontrol packet Cl is set to be different from a logic level of secondidentification informations C16 and C17 encoded to each of the sourcecontrol packets Cf, Cb, and Cr. Each of the source drive ICs SDIC#1 toSDIC#8 may confirm whether or not the real source control packet Cr isinput depending on the logic level of the first identificationinformations C1 and C2 and may predict an input of the RGB data packetdepending on the logic level of the second identification informationsC16 and C17.

In the real source control packet Cr, the polarity-related control dataand the source output-related control data may be encoded in the formillustrated in FIG. 16 or 20.

FIG. 16 is a data mapping table illustrating a first implementation ofthe real source control packet Cr.

As shown in FIG. 16, the source output-related control data includes‘SOE’ of bit C2 of the real source control packet Cr and SOE_PRD[3:0]between bits C4 and C11, and the polarity-related control data includes‘POL’ of bit C14 of the real source control packet Cr.

As shown in FIG. 17, if the SOE&POL restoring unit 74 detects bit C2 ofthe real source control packet Cr, the SOE&POL restoring unit 74generates a pulse of the source output enable signal SOE at a previouslydetermined rising time. Further, the SOE&POL restoring unit 74 detectsSOE_PRD[3:0] in bits C5, C7, C9, and C11 of the real source controlpacket Cr to add the restored reference clock REF(SCLK) illustrated inFIGS. 12 and 13 to a count value of SOE_PRD[3:0]. Hence, the SOE&POLrestoring unit 74 determines a falling time of the source output enablesignal SOE. As a result, the SOE&POL restoring unit 74 generates thesource output enable signal SOE that is kept at a high logic level for apredetermined period of time between the previously determined risingtime and the falling time determined by SOE_PRD[3:0] and is kept at alow logic level for a period of time except the predetermined period oftime.

Further, as shown in FIG. 17, the SOE&POL restoring unit 74 detects bitC14 of the real source control packet Cr to generate the polaritycontrol signal POL. Then, after the SOE&POL restoring unit 74 keeps thepolarity control signal POL at the same logic level during “i”horizontal periods, the SOE&POL restoring unit 74 inverts the polaritycontrol signal POL. For example, the SOE&POL restoring unit 74 detectsbit C14 of the real source control packet Cr to generate the polaritycontrol signal POL and keeps the polarity control signal POL at a highlogic level during 1 or 2 horizontal periods. Then, the SOE&POLrestoring unit 74 inverts the polarity control signal POL to keep thepolarity control signal POL at a low logic level during 1 or 2horizontal periods. In other words, the SOE&POL restoring unit 74 mayinvert a logic level of the polarity control signal POL every 1 or 2horizontal periods.

FIG. 18 illustrates a pulse width of the source output enable signal SOEdetermined depending on SOE_PRD[3:0] of the real source control packetCr.

As shown in FIG. 18, a pulse width of the source output enable signalSOE is determined depending on SOE_PRD[3:0] of the real source controlpacket Cr. More specifically, the source output enable signal SOE mayhave a minimum pulse width when a bit value of SOE_PRD[3:0] is “0000 (orLLLL)”. The source output enable signal SOE may have a maximum pulsewidth when a bit value of SOE_PRD[3:0] is “1111 (or HHHH)”. An optimumvalue of the pulse width of the source output enable signal SOE may varydepending on models of liquid crystal displays. This is because a chargeamount of optimum data of the liquid crystal cells may vary depending onpanel properties such as a resolution and an inversion manner and alsomay be determined by several causes. Accordingly, the pulse width of thesource output enable signal SOE has to vary so as to control a datacharge time of the liquid crystal cells.

The pulse width of the source output enable signal SOE may be controlledby counting a cycle of a serial clock SCLK restored by the clockseparation and data sampling unit 21 depending on SOE PRD[3:0]. 1 cycleof a serial clock SCLK is substantially equal to time of 1 sourcecontrol packet or 1 RGB data packet. In case of a FHD (full highdefinition) liquid crystal display driven at a frame frequency of 120Hz, 1 cycle of a serial clock SCLK is approximately 27.2 ns. In case ofa FHD liquid crystal display driven at a frame frequency of 60 Hz, 1cycle of a serial clock SCLK is approximately 55.2 ns. Accordingly, asshown in FIGS. 18 and 19, in the 120 Hz FHD liquid crystal display, if abit value of SOE_PRD[3:0] is “0000”, the pulse width of the sourceoutput enable signal SOE is reduced to a following value: SCLK×4=27.2ns×4=108.8 ns. Further, if a bit value of SOE_PRD[3:0] is “1111”, thepulse width of the source output enable signal SOE increases to afollowing value: SCLK×64=27.2 ns×64=1740.8 ns.

FIG. 20 is a data mapping table illustrating a second implementation ofthe real source control packet Cr. FIG. 21 is a waveform diagramillustrating the source output enable signal SOE controlled depending onbits C1 and C2 and the polarity control signal POL controlled dependingon bits C13 and C14 in the second implementation of the real sourcecontrol packet Cr.

As shown in FIGS. 20 and 21, the real source control packet Cr includes‘SOE’ of bits C1 and C2 and ‘POL’ of bits C13 and C14.

When the SOE&POL restoring unit 74 detects bits C1 and C2 of a realsource control packet Cr having a first logic value (H/H), the SOE&POLrestoring unit 74 generates the source output enable signal SOE of ahigh logic level and keeps the source output enable signal SOE at a highlogic level for a predetermined period of time. Then, the SOE&POLrestoring unit 74 reads bits C1 and C2 of another real source controlpacket Cr. When bits C1 and C2 of another real source control packet Crare detected as a second logic value (H/L), the SOE&POL restoring unit74 inverts a logic level of the source output enable signal SOE to a lowlogic level. Accordingly, a pulse width of the source output enablesignal SOE may be automatically adjusted depending on bits C1 and C2 ofthe real source control packet Cr. The pulse width of the source outputenable signal SOE may be adjusted depending on a length of the sourcecontrol packet as illustrated in FIGS. 22A to 22C.

In an example illustrated in FIG. 22A, bits C1 and C2 of a first realsource control packet Cr may include a rising time information HH of thesource output enable signal SOE, and bits C1 and C2 of a fourth realsource control packet Cr may include a falling time information HL ofthe source output enable signal SOE. The SOE&POL restoring unit 74generates the source output enable signal SOE of a high logic level inresponse to a first restoring clock SCLK#1 and keeps the source outputenable signal SOE at a high logic level for a predetermined period oftime from a generation time point of the first restoring clock SCLK#1 toimmediately before a generation of a fourth restoring clock SCLK#4.Then, when the SOE&POL restoring unit 74 detects the falling timeinformation HL in response to the fourth restoring clock SCLK#4, theSOE&POL restoring unit 74 inverts a logic level of the source outputenable signal SOE to a low logic level. Accordingly, the SOE&POLrestoring unit 74 may restore the source output enable signal SOE havinga pulse width corresponding to (4×source control packet length or RGBdata packet length).

In an example illustrated in FIG. 22B, bits C1 and C2 of a first realsource control packet Cr may include a rising time information HH of thesource output enable signal SOE, and bits C1 and C2 of an eighth realsource control packet Cr may include a falling time information HL ofthe source output enable signal SOE. The SOE&POL restoring unit 74generates the source output enable signal SOE of a high logic level inresponse to a first restoring clock SCLK#1 and keeps the source outputenable signal SOE at a high logic level for a predetermined period oftime from a generation time point of the first restoring clock SCLK#1 toimmediately before a generation of an eighth restoring clock SCLK#8.Then, when the SOE&POL restoring unit 74 detects the falling timeinformation HL in response to the eighth restoring clock SCLK#8, theSOE&POL restoring unit 74 inverts a logic level of the source outputenable signal SOE to a low logic level. Accordingly, the SOE&POLrestoring unit 74 may restore the source output enable signal SOE havinga pulse width corresponding to (8×source control packet length or RGBdata packet length).

In an example illustrated in FIG. 22C, bits C1 and C2 of a first realsource control packet Cr may include a rising time information HH of thesource output enable signal SOE, and bits C1 and C2 of a twelfth realsource control packet Cr may include a falling time information HL ofthe source output enable signal SOE. The SOE&POL restoring unit 74generates the source output enable signal SOE of a high logic level inresponse to a first restoring clock SCLK#1 and keeps the source outputenable signal SOE at a high logic level for a predetermined period oftime from a generation time point of the first restoring clock SCLK#1 toimmediately before a generation of a twelfth restoring clock SCLK#12.Then, when the SOE&POL restoring unit 74 detects the falling timeinformation HL in response to the twelfth restoring clock SCLK#12, theSOE&POL restoring unit 74 inverts a logic level of the source outputenable signal SOE to a low logic level. Accordingly, the SOE&POLrestoring unit 74 may restore the source output enable signal SOE havinga pulse width corresponding to (12×source control packet length or RGBdata packet length).

As shown in FIG. 20, the SOE&POL restoring unit 74 detects bits C13 andC14 of the real source control packet Cr to generate the polaritycontrol signal POL. Then, after the SOE&POL restoring unit 74 keeps thepolarity control signal POL at the same logic level during “i”horizontal periods, the SOE&POL restoring unit 74 inverts the polaritycontrol signal POL. For example, the SOE&POL restoring unit 74 detectsbits C13 and C14 of the real source control packet Cr to generate thepolarity control signal POL and keeps the polarity control signal POL ata high logic level during 1 or 2 horizontal periods. Then, the SOE&POLrestoring unit 74 inverts the polarity control signal POL to keep thepolarity control signal POL at a low logic level during 1 or 2horizontal periods. In other words, the SOE&POL restoring unit 74 mayinvert a logic level of the polarity control signal POL every 1 or 2horizontal periods.

Non-uniformity in a charge amount of the data voltage of the liquidcrystal cells that is likely to be generated in an N-dot inversionmanner (where N is an integer equal to or greater than 2) may be solvedusing a method of adjusting the pulse width of the source output enablesignal SOE illustrated in FIGS. 16 to 22C. FIG. 23 illustratesnon-uniformity in a charge amount of the data voltage generated whenpulse widths SOE1 of source output enable signals SOE are uniform in avertical 2-dot inversion manner. In the vertical 2-dot inversion manner,a positive data voltage is supplied to the liquid crystal cells of firstand second lines LINE #1 and LINE #2, and then a negative data voltageis supplied to the liquid crystal cells of third and fourth lines LINE#3 and LINE #4. In the vertical 2-dot inversion manner, each of thesource drive ICs SDIC#1 to SDIC#8 successively outputs the positive datavoltages during 2 horizontal periods and then successively outputs thenegative data voltages during 2 horizontal periods subsequent to the 2horizontal periods. While the liquid crystal cells of the first lineLINE #1 are charged to the positive data voltage through the data linescharged to the negative data voltage, the liquid crystal cells of thesecond line LINE #2 are charged to the positive data voltage through thedata lines charged to the positive data voltage. Accordingly, even ifthe source drive ICs SDIC#1 to SDIC#8 output the positive data voltagesof the same voltage level, a charge amount of the positive data voltageof the liquid crystal cells of the second line LINE #2 is greater than acharge amount of the positive data voltage of the liquid crystal cellsof the first line LINE #1. Further, even if the source drive ICs SDIC#1to SDIC#8 output the negative data voltages of the same voltage level, acharge amount of the negative data voltage of the liquid crystal cellsof the fourth line LINE #4 is greater than a charge amount of thenegative data voltage of the liquid crystal cells of the third line LINE#3. Because of this, a luminance difference between the lines may becaused in the vertical 2-dot inversion manner.

A liquid crystal display according to another embodiment of theinvention adjusts a pulse width of a source output enable signal SOE asillustrated in FIG. 24, so that an output time of liquid crystal cellscharged for a relatively long time is reduced. Each of the source driveICs SDIC#1 to SDIC#8 outputs a first positive or negative data voltagefor a period of time from a falling edge of a first source output enablesignal SOE1 having a relatively narrow pulse width to a rising edge of asecond source output enable signal SOE2 having a relatively wide pulsewidth. Then, each of the source drive ICs SDIC#1 to SDIC#8 outputs acommon voltage or a charge share voltage during a high logic levelperiod of the second source output enable signal SOE2. Further, each ofthe source drive ICs SDIC#1 to SDIC#8 outputs a second positive ornegative data voltage for a period of time from a falling edge of thesecond source output enable signal SOE2 to a rising edge of a next firstsource output enable signal SOE1. Accordingly, because an output time ofthe second positive/negative data voltage is shorter than an output timeof the first positive/negative data voltage, non-uniformity in a chargeamount of data voltages between lines is compensated.

In the liquid crystal display according to the embodiment of theinvention, the pairs of data bus lines DATA&CLK are used to connect thetiming controller TCON to the source drive ICs SDIC#1 to SDIC#8 in thepoint-to-point manner, and a length of the data bus line DATA&CLK variesdepending on a distance between the timing controller TCON and thesource drive ICs SDIC#1 to SDIC#8. In FIG. 2, because a distance betweenthe timing controller TCON and the fourth source drive IC SDIC#4 isshort, a length of the pair of data bus lines DATA&CLK connecting thetiming controller TCON to the fourth source drive IC SDIC#4 is short. Onthe contrary, in FIG. 2, because a distance between the timingcontroller TCON and the first source drive IC SDIC#1 is long, a lengthof the pair of data bus lines DATA&CLK connecting the timing controllerTCON to the first source drive IC SDIC#1 is long. As the length of thepair of data bus lines DATA&CLK increases, an RC delay amount and avoltage drop amount increase. As a result, an RC delay amount and avoltage drop amount in the Phases 1 to 3 signals supplied to the firstsource drive IC SDIC#1 are more than an RC delay amount and a voltagedrop amount in the Phases 1 to 3 signals supplied to the fourth sourcedrive IC SDIC#4.

A liquid crystal display according to another embodiment of theinvention, as shown in FIG. 25, increases a voltage of signals suppliedthrough the pairs of data bus lines DATA&CLK in proportion to a distancebetween the timing controller TCON and the source drive ICs SDIC#1 toSDIC#8. The timing controller TCON allows a swing width Wswing1 ofsignals to be transferred to the third to sixth source drive ICs SDIC#3to SDIC#6 to be relatively narrow and allows a swing width Wswing3 ofsignals to be transferred to the first and eighth source drive ICsSDIC#1 and SDIC#8 to be relatively wide. Further, the timing controllerTCON allows a swing width Wswing2 of signals to be transferred to thesecond and seventh source drive ICs SDIC#2 and SDIC#7 to be greater thanthe swing width Wswing1 and less than the swing width Wswing3. Becauseof the above swing width control, a skew rate time t3 of the signals tobe transferred to the first and eighth source drive ICs SDIC#1 andSDIC#8 is shorter than skew rate times t1 and t2 of the signals to betransferred to the other source drive ICs SDIC#2 to SDIC#7. Further, theskew rate time t2 of the signals to be transferred to the second andseventh source drive ICs SDIC#2 and SDIC#7 is shorter than the skew ratetime t1 of the signals to be transferred to the third to sixth sourcedrive ICs SDIC#3 to SDIC#6. As a result, the liquid crystal displayaccording to another embodiment of the invention can compensate for adelay and a voltage drop of the signals transferred to the first andeighth source drive ICs SDIC#1 and SDIC#8.

A format of the RGB data packet transferred from the timing controllerTCON to the source drive ICs SDIC#1 to SDIC#8 may vary depending on astructure of the pixel array of the liquid crystal display panel 10.

FIG. 26 is an equivalent circuit diagram illustrating an exemplarystructure of the pixel array of the liquid crystal display panel 10.

As shown in FIG. 26, the pixel array of the liquid crystal display panel10 has a structure in which the TFTs are zigzag-connected between theright and left data lines as viewed in a column direction.

The TFTs for driving liquid crystal cells of odd-numbered lines LINE #1and LINE #3 are connected to crossings of odd-numbered gate lines G1,G3, . . . , Gn−1 and the data lines D1 to Dm−1 and supply a data voltagefrom an i-th data line Di to the pixel electrodes 1 of the odd-numberedlines LINE #1 and LINE #3. The TFTs for driving liquid crystal cells ofeven-numbered lines LINE #2 and LINE #4 are connected to crossings ofeven-numbered gate lines G2, G4, . . . , Gn and the data lines D2 to Dmand supply a data voltage from an (i+1)-th data line D(i+1) to the pixelelectrodes 1 of the even-numbered lines LINE #2 and LINE #4. If theliquid crystal display panel 10 is implemented according to the pixelarray structure illustrated in FIG. 26, each of the source drive ICsSDIC#1 to SDIC#8 supplies the data voltages of the same polarity to thedata lines D1 to Dm during 1 frame period and also may supply datavoltages of opposite polarity to adjacent data lines. Because the datavoltages of the same polarity are output to an output channel of each ofthe source drive ICs SDIC#1 to SDIC#8, power consumption of the sourcedrive ICs SDIC#1 to SDIC#8 can be reduced. Further, because the datavoltages of opposite polarity are charged between vertically andhorizontally adjacent liquid crystal cells, the liquid crystal displaypanel 10 may display an image without a flicker and a luminancedifference between lines.

To supply the data voltage to the pixel array shown in FIG. 26, an RGBdata packet of even-numbered lines LINE #2, LINE #4, . . . , LINE #ntransferred from the timing controller TCON to the source drive ICsSDIC#1 to SDIC#8 has to have a different format from an RGB data packetof odd-numbered lines LINE #1, LINE #3, . . . , LINE #(n−1) transferredfrom the timing controller TCON to the source drive ICs SDIC#1 toSDIC#8. The format of the RGB data packet of the odd-numbered lines LINE#1, LINE #3, . . . , LINE #(n−1) illustrated in FIG. 27A issubstantially equal to the format of the RGB data packet illustrated inFIGS. 12 and 13. When data is written to pixels of the even-numberedlines LINE #2, LINE #4, . . . , LINE #n, the first data line D1 is adummy data line that is not connected to the TFT and the liquid crystalcell and the other data lines D2 to Dm are connected to the liquidcrystal cells via the TFTs. As shown in FIG. 27B, 1 RGB data packet tobe written to the pixels of the even-numbered lines LINE #2, LINE #4, .. . , LINE #n successively includes a dummy clock DUM, a clock CLK,10-bit B data of a previous pixel B1 to B10, 5-bit R data R1 to R5, adummy data enable clock DE DUM, a data enable clock DE, 5-bit R data R6to R10, and 10-bit G data G1 to G10 in the order named.

FIG. 28 is a waveform diagram illustrating an output of the clockseparation and data sampling unit 21 when each of R data, G data, and Bdata is 10-bit data.

In the liquid crystal display and the method of driving the sameaccording to the embodiment of the invention, the RGB data packet andthe control data packet are not limited to the data length illustratedin FIGS. 10 to 16 and their length conversion is possible depending on abit rate of an input image as illustrated in FIGS. 29A to 29D.

When each of R data, G data, and B data is 10-bit data, as shown in FIG.29A, the timing controller TCON generates 1 source control packet or 1RGB data packet as a bit stream including DUM, CLK, R1 to R10, G1 to G5,DE DUM, DE, G6 to G10, and B1 to B10 for T hours. The clock separationand data sampling unit 21 of each of the source drive ICs SDIC#1 toSDIC#8 generates 34 edge clocks and 34 center clocks from the 1 sourcecontrol/RGB data packet received from the timing controller TCON andsamples source control bits or RGB data bits in conformity with thecenter clocks.

When each of R data, G data, and B data is 8-bit data, as shown in FIG.29B, the timing controller TCON generates 1 source control/RGB datapacket as a bit stream including DUM, CLK, R1 to R8, G1 to G4, DE DUM,DE, G5 to G8, and B1 to B8 for T×(28/34) hours. The clock separation anddata sampling unit 21 of each of the source drive ICs SDIC#1 to SDIC#8generates 28 edge clocks and 28 center clocks from the 1 sourcecontrol/RGB data packet received from the timing controller TCON andsamples source control bits or RGB data bits in conformity with thecenter clocks.

When each of R data, G data, and B data is 6-bit data, as shown in FIG.29C, the timing controller TCON generates 1 source control/RGB datapacket as a bit stream including DUM, CLK, R1 to R6, G1 to G3, DE DUM,DE, G4 to G6, and B1 to B6 for T×(22/34) hours. The clock separation anddata sampling unit 21 of each of the source drive ICs SDIC#1 to SDIC#8generates 22 edge clocks and 22 center clocks from the 1 sourcecontrol/RGB data packet received from the timing controller TCON andsamples source control bits or RGB data bits in conformity with thecenter clocks.

When each of R data, G data, and B data is 12-bit data, as shown in FIG.29D, the timing controller TCON generates 1 source control/RGB datapacket as a bit stream including DUM, CLK, R1 to R12, G1 to G6, DE DUM,DE, G7 to G12, and B1 to B12 for T×(40/34) hours. The clock separationand data sampling unit 21 of each of the source drive ICs SDIC#1 toSDIC#8 generates 40 edge clocks and 40 center clocks from the 1 sourcecontrol/RGB data packet received from the timing controller TCON andsamples source control bits or RGB data bits in conformity with thecenter clocks.

The timing controller TCON decides a bit rate of input data and mayautomatically convert the length of the source control/RGB data packetas illustrated in FIGS. 29A to 29D.

A liquid crystal display according to another embodiment of theinvention generates a preamble signal including a plurality of pulsegroups each having a different pulse width and a different cycle asPhase 1 signals and thus may more securely lock a phase and a frequencyof internal clock pulses output from the PLL of the clock separation anddata sampling unit 21.

FIGS. 30 and 31 are waveform diagrams illustrating Phase 1 signalsaccording to another embodiment of the invention.

As shown in FIGS. 30 and 31, Phase 1 signals include a phase 1-1 signaland a phase 1-2 signal. The phase 1-1 signal is a signal whose 1 cycleis set at the same time as 1 source control/RGB data packet in the samemanner as the above-described preamble signal. A frequency of the phase1-2 signal is greater than a frequency of the phase 1-1 signal, and acycle of the phase 1-2 signal is equal to or less than ½ of a cycle ofthe phase 1-1 signal. The phase 1-2 signal may have a waveform in whichtwo pulse groups P1 and P2 each having a different phase and a differentfrequency are alternately generated. A frequency of the first pulsegroup P1 is equal to or greater than two times a frequency of a pulserow generated in the form of the phase 1-1 signal, and a frequency ofthe second pulse group P2 is equal to or greater than two times thefrequency of the first pulse group P1. As shown in FIGS. 30 and 31,while the PLL 64 of the clock separation and data sampling unit 21tracks pulses whose a frequency is greater than the frequency of thephase 1-1 signal and a phase regularly changes, the clock separation anddata sampling unit 21 can more stably and more rapidly lock a phase anda frequency of internal clock pulses than the preamble signal of the lowfrequency illustrated in FIG. 10.

As consumers have demanded operation improvement of LCD modules, LCDmodule makers may provide the source drive ICs SDIC#1 to SDIC#8 withvarious options so that the consumers may directly control detailedoperations of the LCD modules. For this, in the related art, the makersprovided the source drive ICs SDIC#1 to SDIC#8 with a plurality ofoption pins and connected pull-up resistors or pull-down resistors tothe option pins of the source drive ICs SDIC#1 to SDIC#8 whenevernecessary. Further, in the related art, option operations of the sourcedrive ICs SDIC#1 to SDIC#8 were controlled by applying a power sourcevoltage Vcc or a ground level voltage GND to the LCD module. However, inthe related art, the chip size of the source drive ICs SDIC#1 to SDIC#8increased because of the plurality of option pins, and also the PCB sizeincreased because of pull-up/pull-down resistors connected to the optionpins and lines.

A liquid crystal display according to another embodiment of theinvention may further reduce the chip size of the source drive ICsSDIC#1 to SDIC#8 and the PCB size by adding signals for controllingvarious operations of the source drive ICs SDIC#1 to SDIC#8 during apredetermined period of Phase 2. For this, the liquid crystal displayaccording to the embodiment of the invention generates control optioninformation for controlling various operations of the source drive ICsSDIC#1 to SDIC#8, such as PWRC1/2, MODE, SOE_EN, PACK_EN, CHMODE,CID1/2, H_(—)2DOT, as a separate source control packet. The sourcecontrol packet including the control option information may be insertedinto a predetermined period of Phase 2 and may be transferred to thesource drive ICs SDIC#1 to SDIC#8 through the pairs of data bus lines.

PWRC1/2 is option information determining an amplification ratio of anoutput buffer of the source drive ICs SDIC#1 to SDIC#8 to select a powercapacitance of the source drive ICs SDIC#1 to SDIC#8, as indicated inthe following Table 1.

TABLE 1 PWRC½ = 11 (HH) High Power Mode PWRC½ = 10 (HL) Normal PowerMode PWRC½ = 01 (LH) Low Power Mode PWRC½ = 00 (LL) Ultra Low Power Mode

MODE is option information determining whether to enable or disable anoutput of a charge share voltage during a high logic level period of thesource output enable signal SOE, as indicated in the following Table 2.

TABLE 2 MODE = 1 (H) Hi_Z Mode Operation (charge share output disable)MODE = 0 (L) Charge-share mode operation (Charge share output enable

SOE_EN is option information determining whether to receive the sourceoutput enable signal SOE in the form embedded in the RGB digital videodata or through separate lines from the source drive ICs SDIC#1 toSDIC#8, as indicated in the following Table 3.

TABLE 3 PACK_EN = 0 (L) PACK_EN = 1 (H) SOE_EN = 0 (L) Forbidden Useinternal SOE SOE_EN = 1 (H) Use external SOE

PACK_EN is option information determining whether to receive thepolarity control signal POL and the gate start pulse GSP to betransferred to the gate drive ICs GDIC#1 to GDIC#4 in the form embeddedin the RGB digital video data or through separate lines from the sourcedrive ICs SDIC#1 to SDIC#8, as indicated in the following Table 4.

TABLE 4 PACK_EN = 1 (H) Enable control packet PACK_EN = 0 (L) Disablecontrol packet (Ignore the value of SOE_EN)

CHMODE is option information determining the number of output channelsof the source drive ICs SDIC#1 to SDIC#8 in conformity with a resolutionof the liquid crystal display, as indicated in the following Table 5.

TABLE 5 CHMODE = 1 (H) 690 Ch. Outputs (691~720 Ch. Disable) CHMODE = 0(L) 720 Ch. Outputs

CID1/2 is option information giving a chip identification code CID toeach of the source drive ICs SDIC#1 to SDIC#8 to independently controlthe source drive ICs SDIC#1 to SDIC#8, as indicated in the followingTable 6. A bit rate of CID1/2 may be adjusted depending on the number ofsource drive ICs. Further, as described above, the source drive ICsSDIC#1 to SDIC#8 may be individually controlled through I²Ccommunication using the timing control TCON and the pair of controllines SCL/SDA. The LCD module makers may select among the control methodusing option information CID1/2 and the control method using through I²Ccommunication.

TABLE 6 CID½ = 00 (LL) Assigning to SDIC#1 CID½ = 01 (LH) Assigning toSDIC#2 CID½ = 10 (HL) Assigning to SDIC#3 CID½ = 11 (HH) Assigning toSDIC#4

H_(—)2DOT is option information controlling a horizontal polarity cycleof the positive/negative analog video data voltage output from thesource drive ICs SDIC#1 to SDIC#8, as indicated in the following Table7. For example, if a bit value of H_(—)2DOT is “1 (H)”, the source driveICs SDIC#1 to SDIC#8 control a polarity of the data voltage in ahorizontal 2-dot inversion manner. In the horizontal 2-dot inversionmanner, the source drive ICs SDIC#1 to SDIC#8 output the data voltagesof the same polarity to the two adjacent data lines. Namely, a polarityof the data voltage is inverted every the two adjacent data lines in thehorizontal 2-dot inversion manner. Hence, the polarities of the datavoltages to which the horizontally adjacent liquid crystal cells arecharged are controlled as follows:“− + + −, . . . , + − − + (or + − − +,. . . , − + + −)”. Further, if a bit value of H_(—)2DOT is “0 (L)”, thesource drive ICs SDIC#1 to SDIC#8 control a polarity of the data voltagein a horizontal 1-dot inversion manner. In the horizontal 1-dotinversion manner, the source drive ICs SDIC#1 to SDIC#8 invert apolarity of the data voltage supplied to the adjacent data lines every 1data line. Hence, the polarities of the data voltages to which thehorizontally adjacent liquid crystal cells are charged are controlled asfollows: “− + − +, . . . , + − + − (or + − + −, . . . , − + − +)”.

TABLE 7 H_2DOT = 1 (H) Horizontal 2-Dot inversion Enable H_2DOT = 0 (L)Horizontal 2-Dot inversion Disable

In the embodiments of the invention, the timing controller TCON has toreceive a feedback lock signal of a high logic level from the lastsource drive IC SDIC#8, so that the timing controller TCON proceeds toPhase 2. More specifically, if PLL locking operations of all of thesource drive ICs SDIC#1 to SDIC#8 are not completed, the timingcontroller TCON repeatedly generates only the preamble signal of Phase1, and the source drive ICs SDIC#1 to SDIC#8 do not output the datavoltage. Accordingly, if the timing controller TCON does not receive thefeedback lock signal, an individual driving state of the source driveICs SDIC#1 to SDIC#8 cannot be confirmed. However, a defective sourcedrive IC among the source drive ICs SDIC#1 to SDIC#8 needs to beconfirmed, and also a driving state of each of the source drive ICsSDIC#1 to SDIC#8 needs to be confirmed.

A liquid crystal display according to another embodiment of theinvention provides a test mode and inputs a feedback lock signal to thetiming controller TCON in the test mode to induce an output of the datavoltage of the source drive ICs SDIC#1 to SDIC#8, so as to confirm anindividual driving state of the source drive ICs SDIC#1 to SDIC#8. Forthis, in the liquid crystal display according to the embodiment of theinvention, as shown in FIG. 32, a selection unit SEL is additionallyinstalled inside or outside the timing controller TCON.

More specifically, a first input terminal of the selection unit SEL isconnected to the feedback lock check line LCS2, and a second inputterminal of the selection unit SEL is connected to an input terminal ofa test mode enable signal TEST. The selection unit SEL may beimplemented as an OR gate outputting at least one of a feedback locksignal “Lock Out” and the test mode enable signal TEST. Even if thefeedback lock signal “Lock Out” of a high logic level is not input tothe timing controller TCON, the selection unit SEL inputs the test modeenable signal TEST of a high logic level to a data transfer module ofthe timing controller TCON if the test mode enable signal TEST of thehigh logic level is input. Accordingly, even if the timing controllerTCON does not receive the feedback lock signal in the test mode, thetiming controller TCON may proceed to step S8 of FIG. 6 to transferPhase 2 signals and Phase 3 signals to the source drive ICs SDIC#1 toSDIC#8. The timing controller TCON codes test data extracting from aninternal memory in the test mode to the RGB data packet of Phase 3 andtransfers the coded test data to the source drive ICs SDIC#1 to SDIC#8.An operator watches an image of the test data displayed on the liquidcrystal display panel in the test mode and may confirm the individualdriving state of the source drive ICs SDIC#1 to SDIC#8 and whether ornot there is a detective source drive IC among the source drive ICsSDIC#1 to SDIC#8.

As described above, in the liquid crystal display and the method ofdriving the same according to the embodiments of the invention, a clockgenerating circuit for data sampling is embedded inside each of thesource drive ICs, and the source control packet and the RGB data packetare transferred to each of the source drive ICs through the pair of databus lines. Hence, the number of data transfer lines required between thetiming controller and the source drive ICs can be reduced. Further,because a swing width of the signals transferred to the source drive ICsincreases in proportion to a distance between the timing controller andthe source drive ICs, a deviation in a delay amount of signals input tothe source drive ICs and a deviation in a voltage drop amount of thesignals can be compensated.

Furthermore, in the liquid crystal display and the method of driving thesame according to the embodiments of the invention, the control linesare connected between the timing controller and the source drive ICs,and the timing controller transfers the chip identification code and thecontrol data to the source drive ICs through the control lines. Hence,the source drive ICs can be individually controlled and thus canindependently perform a debugging operation.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the scope of the principles of thisdisclosure. More particularly, various variations and modifications arepossible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

1. A liquid crystal display comprising: a timing controller; N sourcedrive integrated circuits (ICs), where N is an integer equal to orgreater than 2; N pairs of data bus lines, each of which connects thetiming controller to each of the N source drive ICs in a point-to-pointmanner; a lock check line that connects a first source drive IC of the Nsource drive ICs to the timing controller and cascade-connects the Nsource drive ICs to one another; and a feedback lock check line thatconnects a last source drive IC of the N source drive ICs to the timingcontroller, wherein the timing controller serially transfers a preamblesignal, in which a plurality of bits having a high logic level aresuccessively arranged and then a plurality of bits having a low logiclevel are successively arranged, to each of the N source drive ICsthrough each of the N pairs of data bus lines, transfers a lock signalindicating that a phase of an internal clock pulse output from each ofthe N source drive ICs is locked to the first source drive IC throughthe lock check line, receives a feedback signal of the lock signal fromthe last source drive IC through the feedback lock check line, andserially transfers at least one source control packet for controlling adata voltage output from each of the N source drive ICs to each of the Nsource drive ICs through each of the N pairs of data bus lines, whereina swing width of an output voltage of the timing controller includingthe preamble signal, the lock signal, and the source control packetincreases in proportion to a distance between the timing controller andthe N source drive ICs.
 2. The liquid crystal display of claim 1,wherein after the timing controller serially transfers the sourcecontrol packet, the timing controller serially transfers at least oneRGB data packet to each of the N source drive ICs through each of the Npairs of data bus lines, wherein a swing width of a voltage of the RGBdata packet supplied to the N source drive ICs increases in proportionto the distance between the timing controller and the N source driveICs.
 3. The liquid crystal display of claim 2, wherein the RGB datapacket successively includes clock bits, first RGB data bits, internaldata enable clock bits, and second RGB data bits in the order named. 4.The liquid crystal display of claim 3, wherein each of the N sourcedrive ICs restores a first reference clock from the preamble signal tooutput the first reference clock and a first internal clock pulse whosea phase is locked, wherein if the phases of the first internal clockpulses output from the N source drive ICs are locked, the last sourcedrive IC transfers the feedback signal of the lock signal to the timingcontroller through the feedback lock check line, and then each of the Nsource drive ICs restores source control data from the source controlpacket, wherein each of the N source drive ICs restores a secondreference clock from the clock bits included in the RGB data packet,samples RGB data included in the RGB data packet based on the secondreference clock and a second internal clock pulse whose a phase islocked, and converts the RGB data into a positive or negative datavoltage depending on the source control data to output thepositive/negative data voltage.
 5. The liquid crystal display of claim4, wherein the source control data includes: a polarity control signaldetermining a polarity of the positive/negative data voltage that isoutput from each of the N source drive ICs and is supplied to data linesof a liquid crystal display panel; and a source output enable signalthat controls an output timing of the positive/negative data voltageoutput from each of the N source drive ICs.
 6. The liquid crystaldisplay of claim 5, wherein the source control data includes: anactivation information of the source output enable signal; a pulse widthinformation of the source output enable signal; and an activationinformation of the polarity control signal.
 7. The liquid crystaldisplay of claim 6, wherein a pulse width of the source output enablesignal is determined by a multiplication of a length of one of thesource control packet and the RGB data packet by “i”, where i is anatural number, depending on the pulse width information of the sourceoutput enable signal.
 8. The liquid crystal display of claim 5, whereineach of the N source drive ICs outputs a first positive data voltage, asecond positive data voltage, a first negative data voltage, and asecond negative data voltage in the order named, wherein the sourceoutput enable signal includes first pulses for controlling an outputtiming of each of the first positive data voltage and the first negativedata voltage and second pulses for controlling an output timing of eachof the second positive data voltage and the second negative datavoltage, wherein a width of the second pulse is greater than a width ofthe first pulse.
 9. The liquid crystal display of claim 4, wherein theRGB data packet includes a first RGB data packet to be displayed onodd-numbered lines of a liquid crystal display panel and a second RGBdata packet to be displayed on even-numbered lines of the liquid crystaldisplay panel, wherein an RGB data arrangement order in the first RGBdata packet is different from an RGB data arrangement order in thesecond RGB data packet.
 10. The liquid crystal display of claim 9,wherein the first RGB data packet successively includes R data of afirst pixel, G data of the first pixel, and B data of the first pixel inthe order named, wherein the second RGB data packet successivelyincludes B data of a second pixel, R data of a third pixel, and G dataof the third pixel in the order named.
 11. The liquid crystal display ofclaim 10, wherein the first RGB data packet further includes clock bitsarranged prior to the R data of the first pixel and internal data enableclock bits arranged between first G data of the first pixel and second Gdata of the first pixel, wherein the second RGB data packet furtherincludes clock bits arranged prior to R data of the second pixel andinternal data enable clock bits arranged between first R data of thethird pixel and second R data of the third pixel.
 12. The liquid crystaldisplay of claim 11, wherein each of the N source drive ICs adjusts apulse width of the source output enable signal by a multiplication of alength of one of the source control packet and the RGB data packet by“i”, where i is a natural number, depending on the pulse widthinformation of the source output enable signal.
 13. The liquid crystaldisplay of claim 11, wherein the timing controller serially transfers atleast one second source control packet for controlling the data voltageoutput from each of the N source drive ICs to each of the N source driveICs through each of the N pairs of data bus lines, wherein the secondsource control packet includes at least one of PWRC1/2 optioninformation determining an amplification ratio of an output buffer ofeach of the N source drive ICs, MODE option information determining anoutput of a charge share voltage of each of the N source drive ICs,SOE_EN option information determining a receiving path of the sourceoutput enable signal, PACK_EN option information determining a receivingpath of the polarity control signal, CHMODE option informationdetermining the number of output channels of the N source drive ICs,CID1/2 option information that gives a chip identification code to eachof the N source drive ICs to independently control the N source driveICs, and H_(—)2DOT option information determining a horizontal polaritycycle of the positive/negative data voltage output from the N sourcedrive ICs.
 14. The liquid crystal display of claim 2, wherein after thetiming controller receives at least one of the feedback signal of thelock signal and a predetermined test mode enable signal, the timingcontroller serially transfers the source control packet and the RGB datapacket to each of the N source drive ICs through each of the N pairs ofdata bus lines.
 15. The liquid crystal display of claim 1, furthercomprising a pair of control lines connecting in parallel the timingcontroller to the N source drive ICs, wherein the timing controllertransfers a chip identification code for individually indentifying the Nsource drive ICs and control data controlling functions of each of the Nsource drive ICs to the N source drive ICs through the pair of controllines.
 16. A method of driving a liquid crystal display including atiming controller and N source drive integrated circuits (ICs), where Nis an integer equal to or greater than 2, the method comprising:generating a preamble signal, in which a plurality of bits having a highlogic level are successively arranged and then a plurality of bitshaving a low logic level are successively arranged, from the timingcontroller; serially transferring the preamble signal to each of the Nsource drive ICs through each of N pairs of data bus lines connectingthe timing controller to the N source drive ICs in a point-to-pointmanner; generating a lock signal indicating that a phase of an internalclock pulse output from each of the N source drive ICs is locked fromthe timing controller; transferring the lock signal to a first sourcedrive IC of the N source drive ICs through a lock check line thatconnects the first source drive IC to the timing controller andcascade-connects the N source drive ICs to one another; generating afeedback signal of the lock signal from a last source drive IC of the Nsource drive ICs; transferring the feedback signal of the lock signal tothe timing controller through a feedback lock check line connecting thelast source drive IC to the timing controller; generating at least onesource control packet for controlling a data voltage output from each ofthe N source drive ICs from the timing controller; and seriallytransferring the source control packet to each of the N source drive ICsthrough each of the N pairs of data bus lines, wherein a swing width ofan output voltage of the timing controller including the preamblesignal, the lock signal, and the source control packet increases inproportion to a distance between the timing controller and the N sourcedrive ICs.
 17. The method of claim 16, further comprising: afterserially transferring the source control packet, generating at least oneRGB data packet from the timing controller; and serially transferringthe RGB data packet to each of the N source drive ICs through each ofthe N pairs of data bus lines.
 18. The method of claim 17, furthercomprising: restoring a first reference clock from the preamble signalinside each of the N source drive ICs to output the first referenceclock and a first internal clock pulse, whose a phase is locked, fromeach of the N source drive ICs; if the phases of the first internalclock pulses output from the N source drive ICs are locked, transferringthe feedback signal of the lock signal generated by the last sourcedrive IC to the timing controller through the feedback lock check line;restoring source control data from the source control packet inside eachof the N source drive ICs; restoring a second reference clock from clockbits included in the RGB data packet inside each of the N source driveICs to output the second reference clock and a second internal clockpulse, whose a phase is locked, from each of the N source drive ICs;sampling RGB data included in the RGB data packet based on the secondinternal clock pulses; and converting the RGB data into a positive ornegative data voltage depending on the source control data inside eachof the N source drive ICs to output the positive/negative data voltage.19. The method of claim 18, wherein the RGB data packet includes a firstRGB data packet to be displayed on odd-numbered lines of a liquidcrystal display panel and a second RGB data packet to be displayed oneven-numbered lines of the liquid crystal display panel, wherein thefirst RGB data packet successively includes R data of a first pixel, Gdata of the first pixel, and B data of the first pixel in the ordernamed, wherein the second RGB data packet successively includes B dataof a second pixel, R data of a third pixel, and G data of the thirdpixel in the order named.
 20. The method of claim 19, wherein the firstRGB data packet further includes clock bits arranged prior to the R dataof the first pixel and internal data enable clock bits arranged betweenfirst G data of the first pixel and second G data of the first pixel,wherein the second RGB data packet further includes clock bits arrangedprior to R data of the second pixel and internal data enable clock bitsarranged between first R data of the third pixel and second R data ofthe third pixel.